Method and machine for forming corrugated tubing



April 29, 1947. P..DUENAS ET AL 2,419,678

METHOD AND MACHINE FOR FORMING CORRUGATED TUBING Filed Sept. 14, 1945 2 Sheets-Sheet 1 INVENTORS PETER DUE/VAS L/OH/V 0 NA April 29, 1947. R DUENAS ET'AL 2,419,678

METHOD AND MACHINE FOR FORMING CORRUGATED TUBING Filed Sept. 14, 1943 2 Sheets-Sheet 2 INVENTORS PETE/Q OUENAS JOHN 00 M45 TORNEYS MET OD ANDMACHIN, sloiiime CORRUGATED'TUBING 1 ,Z Our invention ;.relat.esj to. the manufacture of cz irrng'aieatubmg .onmetal'lios'e for the purpose go" conferring .fiexibilityiandior such other purses as may .be desired."

lfto theiiormation of corrugations or helical, circular or hther circumferent "form; but it is more i par icu arlyappraise;t ,Ithe fffo'rmation of the "helical type of corrugation an metaitubmg.

t, y In a known process of formihglhelical corru gations in .metal tubinggthertubing is passed through an unyielding ,form'in'g die by a coinpositelrotary and longitudinal movement, the "die having a corrugation-formingthread or helix' in-i TI creasing in height and decreasing in pitchfin the .l' directionlin which the tube progresses through -the die. LAn" innerimandrel or core limits the 'fl inward "displacement voflthe metal; wall and hence the inner {diameter ofthe corrugation, while the die isl'so..formed as v to limitf-the outerdiameter of j the corrugations to the outer diameter of thetube which the corrugations are'being Yforme'd. In suchlpr ocess, the deformation of the metal both [egatmnsi is opposed at one and t sj me time Qby, the internal resistance of the metal to. deiormat ion and thel-frictionfof, the inner and outer surfaces of the metal wall: with the 'idrming'die 1 1n' .genera1 way,;thefinv ention is applicable inwardl'yand in aiiial-hirection to form' the cor- 1 I Peter Duenas a'nd 'John Duenas, Fo'rest Hills-N; j Applicatiomseptember 14, 943,; seria1 i\i6 "03,252

- 4 G'lai'ms. (o

it 'e'c me possible to commerciallyfprodube corrugated m tal "tubing df'"much greaterfslze, f'wallthickness and depth of corrugation. ,ie'siiitii ccom lishedby' thefapp at of "ter'rnit'te Iit', pressure inwardly against the tribe wanb ayielding die" member"actuatedfby'p we Ydri'vfe vibratory means while feeding "the'tube ,ithriigh 'the the ma rotary and axial direction. I fTheflinw rdfdisplacement of themet'al'iis thus accomplished; by I direct inwardly-applied vibra- 'tory' pressure; and the axial displacement is 'acmplishedthe turnin of the tube within'the e nder', conditions of 'grea'tlyireduced 'sinface n ctic Tofacilitaitethis'operatiomthe le employed fbr the forming operationfmust he in "at least twojp'a'r' and: preferably three or more ipa'rts; part, being more than 180"ih1gircumference anfd referably somewhat less, The diepart-sQare' complementary; and one is movable with,respe so the, other in a, direction to iopen and clos' upon; the metal tube passing through 'thediedur' gt'heforrning operation. This openirigjl (":loslhg motion is effected transversely of and the mandrel-or core. .The force necessary to overcome the eXternal-Qfriction and the internal resistance must necessarily be transmitted by --the tube itself. This limits the power which can "be delivered at the locus of the 'forming operation, and hence restricts commercial production of corrugatedmetal tubing of a given metal or ii l' ta quite m ed. ia eter a i kne an depth of corrugation." f J I j i An important object of the invention is to vfacilitate.the commercial production .of'corrugated metal tubing and make possible the production .of same in greater dimensions such, as diameter depth of corrugation and; wall thick- ,ness. Incidental to the attainment of thesenob- .j-ects it becomes possible withinthe principles of the invention to readilyproduce corrugated metal tubing of given dimensions of :metals and alloys which have notheretofore been susceptible of forming into corrugated shapes, for example, steel tubing of comparatively heavy walls and large diametert I fccording to our invention, the power neceslsary to displace themetal'inwardly and in an axial direction to form the corrugations is transihiitted only n part by the turning of "the tube, andth'e surface friction 'is' greatly reduced; so"

, tfhe cift h tubing; and need "he" little n'iore vtheir,'sj iif fici'en't tohalternately' grip and free' the contact ng .c surfa'ces'j of the tubing and moving illustrative embodiment of the inventionfis represented in the accompanying drawing, ich-a P '3 Fi'gurje ,is aflongitudinal elevation of .amac'hfine l with a llehgth of tubing 'in the course of being process gt fisanen'l'aitged Vertical section ofthe 'jmechariisnns'hownflin Figurefl'. Figure iflsa side elevation of'the'iormih'g' die 'rnch'ani's s'hownin Figure Z, and

Figur'4 is-an enlarged, detail elevation at the ftubing 'with parts .in se'ction,' illus'tratingthe lie- 40 p'asse'sthr'oughfihe [forming die.

'veloprnent of the corrugations in the tubing asit Whereas theinvention' is applicable in a broad sense to-theproductionof either helical or strictly circular corrugations, the machine selected-for tion' o'f a' helical corrugation in metal tubing; it

purposes of'illustration is-designed for the formabe'in'g, of course," 11nderstood that :other types :of mechanism capable ;of. performing substantially the-same operations may be employed within the scope of-our;invention. g i t ;As.seeni-n Figure 1, the machine embodiesthe trackbed w mountedon feet II and the forming die bed l2 Th'ere is provided carriage l3 ,free 'ito'fm ve along theftrack I O on'the rollers, Hand 'fiftd thhOllOW' Spindle l5 which 'is'liilvn from the machine, and a guide bearing 24 sup ported on the adjustable pedestal or foot 25 may guide the tubing on its way to the forming mechanism, which will now be described.

The forming die bed l2 may be in the form of a casting having the side frames 26, 21 intetion occurs largely as a result of the turning of the tube within the die.

In operating the machine, the vibrator is set -in motion. and a length of tubing 2| is passed through guide 24 into the entrance of the forming die and turned either by hand or by wrench until the end projects through the exit of the die sulfl ciently to be gripped by the chuck 20. The carriage I3 is moved to the left (in Figure i) so as to enable the chuck to engage the tube close to the forming die. The motor [5 is then started which rotates the tube continuously at the same grally united or otherwise joined across the top w by the cross member or block 28, as clearl v illustrated in Figures 2 and 3. The side frames 26, 21. provide bearings for a shaft 29 driven by the belt pulley 30 of the vibratory apparatus. Shaft 29 has keyed thereon a cam wheel 3| of waved v contour to engage a roller 32 which is mounted on'a shaft 33 journalled in the arms 34 of a U-sliaped plunger 35. The plunger 35 has grooved sides 36, 31 which slide up and downon tracks or ways 38, 39 vertically mounted on the ffside frames 26, 21 of the forming die bed l2. The lunger 35 is thus free to move up and down in a vertical path between the side frames 25 and 21. Compression springs 40, 4|, which may be guided on vertical pins or rods 42, 43 mounted in the bed member l2, normally urge the plunger 35 upward but yield to the downward movement of the plunger under the influence of the cam wheel 3| upon the roller 32, the plunger 35 being provided with suitable bores 44, 45 to freely receive' the upper ends of the rods 42, 43.

' The lower forming die member 46 may be secured to the forming die bed I2 by countersunk bolts 41, 48, and the upper forming die member 49'may be secured to the under surface of the plunger 35 by countersunk bolts 50, 5!. Only two die] parts are shown to illustrate the principle of a yielding die member which may be actuated by suitable mechanism to intermittently open and closethe die while the tubing is being passed therethrough.

For the formation of a helical corrugatiomthe plurality of die members may carry complemen- 1 tary portions of the corrugation-forming rib or helix, as apparent from Figures 2 and 3 of the drawing. The form of this rib or helix may, if

desired, be such as to produce a helix of somewhat larger outside diameter than the original "tube which is being corrugated. At the entrance to the die, the forming rib is of shallow depth or height and relatively great pitch, and as it "progresses towardjthe exit, the height or depth increases and the pitch decreases. Thus, as seen in Figure 2, the forming thread, or rib starts at 52; as a shallow or low rib of high pitch and proceeds through the-stages 53, 54 and 55 to the stage indicated at 56, the first turn demarking a portion of the tube length which is to constitute "one corrugation, and the successive turns operating upon the metal to displace the trough'inward and reduce the axial length while permitting its outer diameter to expand or increase under the axial reduction in length. The inward displacement -of the troughs is accomplished largely by I the vibration of the die which occurs transversely or. the axis, andthe displacement in axial direc position on the tube close up to .the forming die,

whereupon the chuck is again clamped on the tube and the motor started to resume the operation described. In practical operation, the corrugated tube is readilymade inany desired length by welding a fresh tube onto the trailing end of each tube as the rear end approaches theforming die, the machine being stopped temporarily for each welding.

The rate of rotation with relation to the frequency of the vibration may be varied. Thus, the tube may be inserted while the die is being vibrated, at, for example, thirty vibrations'per sec- 0nd, and after gripping the end of the tube with the chuck 20, the motor maybeestarted and the I speed varied while observing the smoothness and ease with which the corrugations are produced, until the point is attained at which the minimum effort and the smoothest operation is obtained, which may occur, for example, in agiven case when the circumferential travel of the tube surfaceamounts to one sixteenth of an inch per vibration. By reference to Figure 4, the deformation or displacement of the metal will be apparent. Between the points A and B,tlie distance along the surface of the metal should be substantially equal to that between the points B and C, or c and D, or D and E, etc. The v brati n of the die creates the depressions illustrated, and the turning of the tube causes the point B to approach the point A, the point C to approach the point B, the point D to approachthe' point C, the point E toapproach the pointD, etc., until the last one or two convolutions of the forming rib arereached in the die, whereupon the axial displacement of the metal ceases. Theapproach of these respectivepoints toward each other in an axial direction has the eiTect of decreasing the pitch and at the same timeincreasing the outer diameter of the corrugation. Such an operation would encounter very serious surface friction were it not for the fact that the vibration of the yielding die member intermittently reduces the pressure of contact orfre es the contacting surfaces fromeach'other, these operations alternatingwith the application'of the die pressure transversely of 'the axis to-develop'the depth of the troughs. While there maybe some circumferential flow of the metal due tothe continuance of the twisting moment while the vibratory die member is applying thev transverse pressure on'the tube wall, this effect is believed to be purely incidental, and may be so slight as to be. ahnost ne ligible. The formin operation completes the corrugated tube substantially without appreciable change in the wall thickness. The intermittent gripping and freeing of the tube surface during the turning of the tube greatly reduws the drag or friction in the forming operation, and greatly facilitates the passage of the tube through the forming die.

The illustrative example above described obtains relative rotary motion between the forming die and the tube by holding the die and rotating the tube, but it will of course be apparent that the principle involved is the same whether the tube or the die or both be rotated in such way as to obtain turning motion of one with respect to the other.

We claim:

1. Method of corrugating metal tubing which comprises supporting, guiding and rotating metal tubing by the application of supporting, guiding and rotating instrumentalities substantially entirely to the outer wall surface of the tubing, while maintaining the interior of the metal tubing substantially free and unobstructed throughout its length, and simultaneously depressing the troughs and raising the ridges of the corrugations by intermittently applying and releasing metal deforming pressure in the form of a succession of intermittent pressure impulses to the outer wall of the tubing as it rotates.

2. A method of forming corrugated metal tubing which comprises gripping, supporting and applying to the tubing at one portion of its length a rotary driving force leaving the tubing freedom of axial motion, and simultaneously depressing the troughs and raising the ridges of the corrugations by intermittently applying to the outer wall of the rotating tubing at another portion of its length a succession of pressure impulses alternating with pressure releases directed transversely of the tubing axis as the tubing continues to rotate and due to the rotation of the tubing progressing circumferentially around the tubing Wall.

3. A method of corrugating metal tubing which comprises depressing the metal wall to a reduced internal diameter by applying metal deforming pressure substantially entirely to the outer wall of the tubing in the form of a succession of pressure impulses alternating with pressure releases at a portion of its length free to yield inwardly, and simultaneously gripping and applying to the tubing at another portion of its length a rotary driving force leaving the tubing freedom of motion in an axial direction, whereby the said pressure impulses progress circumferentially of the tubing and the tubing is left free to move axially in response to axial pressure resulting from the application of the metal deforming pressure.

4. Apparatus for corrugating metal tubing comprising in combination a forming die adapted to receive the metal tubing, means for supporting said die and holding it against axial displacement, gripping and rotating means for drivin the metal tubing while it is in said forming die, said means comprising a driven hollow spindle and chuck for receiving the metal tubing, and means for supporting and guiding said gripping and rotating means, permitting it to move freely toward and away from said forming die axially of the metal tubing in response to axial pressure applied by the metal tubing.

PETER DUENAS. JOHN DUENAS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

